Halogenated styrene compounds and very low-loss polymers made therefrom

ABSTRACT

The invention is directed to polymerizable vinyl compounds having halogenated aromatic groups and to a method of synthesizing such compounds. In particular, the invention is directed to polymerizable aromatic vinyl compounds wherein, except for the vinylic hydrogen atoms, aromatic C—H bonds are replaced by C—X bonds, where X is a halogen or other selected substituent having a de minimus number, if any, of C—H bonds; for example, without limitation, highly fluorinated fluoroalkanes. In addition, the compounds of the invention have a de minimus number, if any, of N—H and O—H bonds.

CLAIM OF PRIORITY

This application claims the priority benefit of European ApplicationNumber 02292461.7 filed Oct. 18, 2002.

FIELD OF THE INVENTION

The invention is directed to novel aromatic vinyl compounds, methods ofpreparing such compounds, and their use as polymeric materials. Inparticular, the invention is directed to low-loss, halogenated styrenecompounds and their derivatives that can be used in opticalcommunications devices.

BACKGROUND OF THE INVENTION

In optical communication systems, messages are transmitted byelectromagnetic carrier waves at optical frequencies that are generatedby sources such as lasers and light-emitting diodes. One preferreddevice for routing or guiding waves of optical frequencies from onepoint to another is an optical waveguide. The operation of an opticalwaveguide is based on the fact that when a light-transmissive medium issurrounded or otherwise bounded by an outer medium having a lowerrefractive index, light introduced along the axis of the inner mediumsubstantially parallel to the boundary with the outer medium is highlyreflected at the boundary, trapping the light in the light transmissivemedium and thus producing a guiding effect between channels. A widevariety of optical devices can be made which incorporate such lightguiding structures as the light transmissive elements. Examples, withoutlimitation, include planar optical slab waveguides, channel opticalwaveguides, rib waveguides, optical couplers, optical splitters, opticalswitches, optical filters, arrayed waveguide gratings, waveguide Bragggratings, variable attenuators and the like. For light of a particularfrequency, optical waveguides may support a single optical mode ormultiple modes, depending on the dimensions of the inner light guidingregion and the difference in refractive index between the inner mediumand the surrounding outer medium.

Organic polymeric materials can be used to construct optical waveguideand interconnect devices such as those given above. However, whereassingle mode optical devices built from planar waveguides made from glassare relatively unaffected by temperature, devices made from organicpolymers may show a significant variation of properties withtemperature. This is due to the fact that organic polymeric materialshave a relatively high thermo-optic coefficient (dn/dT). Consequently, achange in temperature causes the refractive index of an optical devicemade from a polymeric material to change appreciably. This ability tohave a change in polymer refractive index due to a temperature changecan be used to make active, thermally tunable or controllable devicesincorporating light transmissive elements. One example of a thermallytunable device is a 1×2 switching element activated by the thermo-opticeffect. In such a device light from an input waveguide may be switchedbetween two output waveguides by the application of a thermal gradientinduced by a resistive heater for which the heating/cooling processesoccur over the span of one to several milliseconds.

A critical requirement for telecommunication devices is to achieve lowinsertion loss; which means that the materials used in waveguides andoptical devices should have low levels of light absorption. Whilespecial, high purity glass has been used in many glasstelecommunications applications, in recent years there has beenconsiderable research into polymeric materials which can be used by thetelecommunications industry instead of glass. Polymers have severaladvantages over glass materials. For example, they can be easilyformulated to specifically match desired properties or can be reactedwith other polymeric material to achieve the desired characteristics;and they can be worked at lower temperatures than glass. However,traditional carbon-hydrogen polymeric materials also have certainundesirable characteristics. In particular, when polymeric materials areused in telecommunications devices, the absorption in the near IR fororganic materials is linked to the presence of E—H covalent bonds (E=N,O or C) that have stretching vibration bands at energies between 2800and 3500 nm. Overtones and combinations bands involving these E—H bondscan increase significantly the absorption loss at 1550 nm. In addition,O—H and N—H bonds, which may be present in polyimides and polyacrylatesfor exemple, contribute very strongly to absorption at wavelengths near1310 nm as well as at 1550 nm. Thus, the presence of O—H and N—H bondsis particularly detrimental to low losses. Thus, the presence of O—H andN—H bonds is particularly detrimental to low losses. Consequently, fortelecommunications uses it would be desirable to produce polymerizableorganic materials that have no or very few C—H, O—H and N—H bonds.Comparatively speaking, it is relatively easy to prepare polymerizablematerials that do not contain O—H and N—H bonds. The removal of all C—Hbonds from a molecular structure is a much more difficult task toaccomplish.

Considerable research has been done concerning the replacement of C—Hbonds by C—F bonds. However, very few organic materials are totallyfluorinated, TEFLON being the best known example. In addition, evenwhere monomeric C—H materials can be fully fluorinated, suchperfluorinated monomers do not polymerize easily. Moreover, it is verydifficult to process such the perfluoro polymers into telecommunicationsdevices such as waveguides and planar devices.

While considerable efforts have been devoted to seeking polymerizablecompounds having fluorinated alkyl attached to a polymerizable moiety,for example, an acrylate group, much less effort has been devoted toseeking novel polymerizable species in which the polymerizable group isdirectly attached to a fluorinated aromatic ring. Examples of compoundshaving fluorinated aromatic rings can be found in the following U.S.Pat. No. (title): 3,637,866 to Pasquale et al (Substituted PerfluoroDiphenyl Ethers); U.S. Pat. No. 3,661,967 to Anderson et al (CyanoContaining Polyfluoroaromatic Compounds); U.S. Pat. No. 4,420,225 toBömer et at (Lens Of A Homo- Or Copolymer Of A Fluorine ContainingStyrene Polymer); and U.S. Pat. No. 6,333,436 B1 (Styrene Derivatives).In particular, there are not many known compounds in which a fluorinatedaromatic ring, and particularly highly fluorinated aromatic rings aredirectly attached to vinylic groups (—CH═CH₂).

Consequently, even though considerable research has been directed to thedevelopment of fluorine containing polymerizable materials, the needexists for addition materials in this area. In particular, therecontinues a need for fluorine containing polymerizable material thathave low absorption losses in the 1550 nm and 1300 nm region in whichtelecommunications devices operate.

SUMMARY OF THE INVENTION

In one aspect, the invention is directed to halogenated aromaticcompounds having polymerizable vinyl groups attached to the aromaticring. The halogenated aromatic compounds of the invention arevinylbenzene (styrene) compounds in which the aromatic ring bearing thevinyl group is ring-substituted by fluorine, chlorine, and otherfluorinated or chlorinated moieties, including mixtures of the foregoingmoieties, and have the general formula P₂C═CH—C₆X_(5-n)Z_(n), where P=Hor D, Z=—Y—C₆X₅,

—Y—W—U-[(o-, m-, or p—C₆X₄—CH═CH₂)]_(m) and mixtures thereof; Y and U,independently, are O, S, NH, or are absent; W is a linking groupselected from the group consisting of aromatic, polycyclic aromatic(fused-ring), 5- or 6-member heterocyclic aromatic, andpolycyclic-heterocyclic (fused ring) compounds containing carbon incombination with one or a plurality of atoms selected from the groupconsisting of O, S and N, including a mixture of such atoms; X=F, Cl,CF₃ and mixtures thereof; and m and n, independently, are an integer inthe range of 1-3. These halogenated aromatic species have very lowoptical absorption losses when operating at telecommunicationswavelengths. The linking groups W may be partially or fully halogenatedand/or deuterated.

In another aspect, the invention is directed to a method of synthesizinghighly halogenated aromatic compounds having polymerizable vinylicgroups.

In yet another aspect, the invention is directed to energy polymerizablecompositions that can used alone or in combination with other energypolymerizable compounds to form a polymeric material that has lowoptical losses in both the C-band and L-band. The energy polymerizablecompositions contain (1) first polymerizable monomer of formulaP₂C═CH—C₆X_(4-n)Z_(n), where P=H or D, Z=—Y—C₆X₅, —Y—W—U-[(o-, m-,p—C₆X₄—CH═CH₂)]_(m), and mixtures thereof; where, independently, Y andU=O, S, NH, or is not present; where W is a linking group selected fromthe group consisting of aromatic, polycyclic aromatic (fused-ring), 5-or 6-member heterocyclic aromatic and polycyclic-heterocyclic compoundsand halogenated derivatives thereof; where X=F, Cl, CF₃ and R_(f), andmixtures thereof, and R_(f) is a C₂-C₅ hydrocarbon in which 50% or moreof C—H bonds are replaced by C—F bonds; and where m and n are integersin the range of 1-3; (2) optionally, a second polymerizable monomer oroligomer having a polymerizable vinylic group; and (3) optionally, apolymerization initiator compound.

In yet another aspect, the invention is directed to optical elements anddevices made from aromatic vinyl compounds having halogens and otherselected substituents present on the aromatic ring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the absorption or propagation losses for variousmolecules versus H per unit volume.

FIG. 2 illustrates the FT-IR spectrum for a monomer of Structure 1 and ahomopolymer formed from the polymer.

FIG. 3 illustrates the FT-IR of a homopolymer made from the monomer ofStructure 1 and a copolymer made from monomer 1 and a fluorinated epoxymonomer.

DETAILED DESCRIPTION OF THE INVENTION

As used herein the term “monomer 1 (or 2, 3, 4, or 5)” means a monomerof corresponding Structure 1, 2, 3, 4 or 5. Also as used herein the term“polycyclic-heterocyclic heterocyclic “refers to a compound in which oneor more nitrogen heterocyclic rings are “fused” to another heterocyclicring or to one or more aromatic rings so that there are atoms common tothe fused rings. The compound of Structure 4 exemplifies such apolycyclic heterocyclic ring linking two styryl moieties. The term“—N<(in ring)” as used herein means that the nitrogen atom is part of aheterocyclic ring as shown in FIG. 4.

The invention is directed to polymerizable vinyl-aromatic compounds inwhich the vinyl-bearing aromatic ring is halogenated and to a method ofsynthesizing such compounds. In particular, the invention is directed topolymerizable aromatic vinyl compounds wherein, except for the vinylichydrogen atoms, aromatic C—H bonds are replaced by C—X bonds, where X isa halogen or other selected substituent and thus have a de minimusnumber, if any, of C—H bonds. In addition, the compounds of theinvention have a de minimus number, if any, of N—H and O—H bonds. Suchcompounds are useful in manufacturing optical elements and devices foruse in optical communications. The utility arises from that fact due tothe absence or de minimus number of C—H, N—H and O—H bonds suchcompounds exhibit low optical absorbance losses at the wavelengths usedin optical communications. In addition, the compounds of the inventioncontain aromatic rings, and in some instances sulfur atoms, which raisethe refractive index of organic materials. High refractive indexmaterials are also useful in the reparation of telecommunicationelements and devices.

The compounds of the invention are energy polymerizable. Energypolymerizable means that they can be polymerized, either alone or incombination with other polymerizable compounds, by application of heat,actinic radiation or electron bean radiation to form homopolymers and/orcopolymers. The energy polymerizable compositions contain (1) firstpolymerizable monomer of formula P₂C═CH—C₆X_(4-n)Z_(n), where P=H or D,Z=—Y—C₆X₅.

—Y—W—U-[(o-, m-, p-C₆X₄—CH═CH₂)]_(m), and mixtures thereof; where,independently, Y and U=O, S, NH, or is not present; where W is a linkinggroup selected from the group consisting of aromatic, polycyclicaromatic (fused-ring), 5- or 6-member heterocyclic aromatic andpolycyclic-heterocyclic compounds and halogenated derivatives thereof;where X=F, Cl, CF₃ and R_(f), and mixtures thereof, and R_(f) is a C₂-C₅hydrocarbon in which 50% or more of C—H bonds are replaced by C—F bonds;and where m and n are integers in the range of 1-3; (2) optionally, asecond polymerizable monomer or oligomer having a polymerizable vinylicgroup; and (3) optionally, a polymerization initiator compound. Theenergy polymerizable composition may contain 1-99 wt. % of the firstpolymerizable monomer (or oligomer thereof); 1-99 wt. % of the optionalsecond monomer (or oligomer thereof) and 0.001 10 wt. % of the optionalinitiator, and preferably from 0.1-6 wt. % of the initiator.

In one embodiment the invention is directed to the synthesis ofcompounds of general formula P₂C═CH—C₆X_(4-n)Z_(n), where P=H or D,Z=—Y—C₆X₅, —Y—W—U-[(o-, or p-C₆X₄—CH═CH₂)]_(m) and mixtures thereof; Yand U, independently=O, S, NH, or nothing; W is a linking group; n is aninteger in the range of 1-3; and m is an integer in the range of 1-3.

The linking group W is selected from the group consisting of aromatic,polycyclic aromatic (fused-ring), 5- or 6-member heterocyclic aromaticand polycyclic-heterocyclic (fused ring) compounds in which at least oneheterocyclic ring is fused to and aromatic ring, and halogenatedderivatives of all the foregoing; X=F, Cl, CF₃ and mixtures thereof. Theheterocyclic rings or the heterocyclic part of polycyclic-heterocyclicrings contain carbon in combination with one or a plurality of atomsselected from the group consisting of O, S and N, including a mixture ofsuch atoms. The heterocyclic part of any W may also contain a —N<(inring, originally as an imine or imide) part to which —CH═CH₂—C₆X₄ moietycan be attached. In addition, one or a plurality of the C—H bonds whichmay be present in W may be replaced by C—X bonds, where X=Cl, F, CF₃ orR_(f), R_(f) being a highly fluorinated C₂-C₅ hydrocarbon and highlyfluorinated meaning that greater than 50% of C—H bonds are replaced byC—F bonds. Examples of W linking compounds include, without limitation,derivatives, including halogenated derivatives, of benzene andnaphthalene having a general formula —C₆H_(4-a)X_(a)— or—C₁₀H_(6-b)X_(b)—, respectively, where a=1-4, b=1-6, and X=Cl, F, CF₃ orR_(f), and the heterocyclic and polycyclic-heterocyclic compoundsdescribed herein.

Representative compounds of the type P₂C═CH—C₆X_(5-n)Z_(n), where P=H orD, X=F and/or Cl, Z=—Y—C₆X₅, and Y=O, S or N, are those having thefollowing Structures 1, 2 and 3.

A compound representative of the type P₂C═CH—C₆X_(5-n)Z_(n), where P=Hor D, X=F and/or Cl; Z=Y—W-[U—(o—, m-, or p-C₆X₄—CH═CH₂)]_(m); where,independently, Y and U=O, S, NH or nothing; and where W is a selectedaromatic or heterocyclic aromatic compound containing carbon incombination with one or a plurality of O, S and N is one havingStructure 5:[2,5-bis[(2,3,5,6-tetrafluoro-4-vinylphenyl)thio]-1,3,4-thiadiazole. Inthis example Y and U are present and equal S.

An addition heterocyclic-containing compound representative of theinvention is represented by Structure 6. The compound of Structure 6contains a fluorinated styryl group N-bonded to a fluorinated maleimidemoiety.

A polycyclic-heterocyclic (fused-ring) compound representative of thetype P₂C═CH—C₆X_(5-n)Z_(n), where P=H or D, X=F and/or Cl;Z=—Y—W-[U—(o-, m-, or p- C₆ X₄—CH═CH₂)]_(m); n=1; and Y and U are notpresent is one having Structure 4. The compounds of Structure 4 isderived from 1,2,4,5-benzenetetracarboxylic acid diimide and containstwo —N<(in ring) moieties as illustrated.

Heterocyclic aromatic compounds useful in practicing the invention are5- and 6-member ring systems containing carbon in combination with atleast one of sulfur, nitrogen and oxygen. In the heterocyclic ringsystems there will be a degree of unsaturation due to the presence ofdouble bonds (e.g., C═N, N═N, C═C). General examples of such 5- and6-member heterocyclic ring systems are derivatives of the followingwhich contain at least two thiol groups, an amino group and a thiolgroup, or a plurality of amino and/or thiol groups: pyridine, s- oras-thiazine, thiazoles, dithiazines, thiadiazines, pyrazine, pyrimidine,pyridazine, indolizine, imidazole, thiadiazoles, thiophene, furan andsimilar compounds known in the art. Further, in the foregoingderivatives C—X bonds may replace ring C—H bonds, where X is Cl, F orCF₃. Specific examples, without limitation, of such derivatives include1,3,4-thiadiazole-2,5-dithiol; 5-amino-1,3,4-thiadiazole-2-thiol;trithiocyanuric acid; 4-amino-2-mercaptopyrimidine;2,4-diamino-6-mercaptopyrimidine; 4,6-diamino-2-mercaptopyrimidine;4,5-diamino-2,6-dimercaptopyrimidine, and similar compounds known in theart. When dithiol compounds are used, the final vinylic compounds inaccordance with the invention will have a structure similar to that ofStructure 5. When a compound having at least one thiol group and oneamino group is used, the final product will be expected to have onestyryl moiety, (P₂C═CH)—C₆X₄—, where P=H or D, X is Cl. F or CF₃,replacing only one amino hydrogen atom due to steric considerations. Thescope of the invention includes any of the above compound and similarcompounds in which heterocyclic ring C—H bonds have been replaced by C—Xbonds, where X=F, Cl, CF₃, R_(f) (R_(f) being defined elsewhere in thisapplication) and D (deuterium).

Polycyclic heterocyclic compounds useful in practicing the invention arethose in which at least one heterocyclic ring is fused to an aromaticring. Examples of such compounds include, without limitation,1,2-difluoro-2,3,5,6-benzenetetracarboxylic acid diimide, alloxazine{benzo[g]pteridine-2,4(1H,3H)-dione}, 2-amino-6-chloropurine,2-amino-6-hydroxy-8-mercaptopurine, 5-aminoindazole, 5-aminoindole,1-aminopyrine, 2-amino-6-purinethiol and similar compounds known in theart, and halogenated derivatives thereof.

The compounds of the invention can be used in the preparation ofpolymers and copolymers slated for use in optical communicationsapplications. In some applications where high refractive indices aredesired, compounds of the invention containing sulfur atoms will befound to be particularly advantageous. Sulfur atoms are alsoparticularly advantageous when the polymer is in contact with metalelectrodes or substrates because they improve adhesion. The halogenatedaromatic vinyl compounds of the invention, also known as halogenatedstyrene compounds, can be homopolymerized or copolymerized with otherpolymerizable compounds having polymerizable carbon-carbon double andtriple bonds. Examples of other compounds suitable for copolymerizationby methods known in the art include other vinylic compounds includingother styrene compounds, vinyl sulfides, acrylates, methacrylates,olefins, acetylene compounds, thiols and polythiols (to form thiolenecompounds) and similar compounds, including halogenated derivatives ofany of the foregoing. Particularly advantageous is the use of compoundsof the invention with acrylates and methacrylates, and especiallyfluorinated acrylates and methacrylates of general formulaCH₂═CA—C(O)—O—R_(f2), where A=H, CH₃, CF₃ and R_(f2), and R_(f2) is ahighly fluorinated C₁-C₁₀ alkyl group. Mixtures of the foregoingcompounds can also be used in forming copolymers with the compounds ofthe invention. For example, the compound of Structure 1 can becopolymerized with a mixture of fluorinated acrylates and/ormethacrylates. Copolymers can be made using 1-99% of the monomer of theinvention with 1-99% of a second monomer as specified herein. Themonomers of the invention can also be oligomerized and these oligomerscan be polymerized with second monomers as specified herein or oligomersof such second monomers.

When homopolymerized the monomer of the invention may optionally includean appropriate thermal initiator or photoinitiator such as one of thosedescribed below. Also optionally, the monomers of the invention can bemixed with a selected second monomer or oligomer and, optionally, aselected thermal initiator or photoinitiator. Further, if the resultingcomposition is too viscous to be used for the desired application, anselected solvent (for example, THF, acetone, methyl ethyl ketone) can beadded in an amount sufficient to make a solution appropriate viscosity.

When preparing optical devices or elements, the composition can beapplied to a substrate by any method known in the art; for example, byspraying, dipping, spin coating, or painting the composition on thesubstrate. A photomask may then be applied if required and thecomposition cured as described herein. Uncured composition can beremoved by the use of an appropriate solvent. Subsequently, suchadditional processing steps as may be required to make the element ordevice can be undertaken.

The compounds of the invention can be homopolymerized or copolymerizedas described above. Such polymerization is facilitated by the use ofactinic radiation, usually UV or visible light, or electron beamradiation, preferably in the presence of a photoinitiator compound. Anyphotoinitiator known in the art to be useful for the polymerization ofcarbon-carbon multiple bonds can be used for such polymerizations. Suchinitiators may be used on amounts of 0.01-10 wt. %, preferable from 0.1to 6 wt. % of the total polymerizable mixture. Examples of suchphotoinitiators, without limit, include aromatic ketones such asbenzophenone, acrylated benzophenone, 2-ethylanthraquinone,phenanthraquinone, benzyl dimethyl ketal and other aromatic ketones, forexample, benzoin, benzoin ethers such as benzoin methyl ether, benzoinisobutyl ether, benzoin phenyl ether, methyl benzoin and other benzoincompounds. Typical commercially available photoinitiators include1-hydroxycyclohexyl phenyl ketone (Irgacure® 184), benzoin, benzoinethyl ether, benzodimethyl ketal (Irgacure 651, Ciba-Geigy),2,2-diethylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one(Darocur® 1173, Ciba-Geigy),1-[4-(2-hydroxyethoxy)phenyl]-2-morpholinopropan-1-one (Darocur 2959),2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Irgacure907), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one(Irgacure 369),poly{1-[4-(1-methylvinyl)phenyl]-2-hydroxy-2-methylpropan-1-one}(Esacure® KIP, Lamberti S.p.A., Gallarate, Italy) and[4-(4-methylphenylthio)-phenyl]phenylmethanone (Quantacure® BMS, GreatLakes Fine Chemicals Ltd., London, Great Britain). The most desiredphotoinitiators are those that do not tend to yellow upon irradiation.Darocur 1173, Irgacure 651, Irgacure 184 and Darocur 2959 mentionedabove are specific examples. For highly halogenated curable compositionsincluding the compounds of the invention, particularly where the halogenis fluorine, photoinitiators such as L-12043 and L-9367 from 3M or afluorinated photoinitiator such as2-(1H,1H,2H,2H-heptadecafluoro-1-decoxy)-2-methyl-1-phenylpropan-1-one(described in U.S. Pat. No. 5,391,587) may be required.

Thermal initiators, which generate free radicals upon heating, may alsobe used in selected amounts to initiate the polymerization ofpolymerizable (curable) compositions containing the compounds of theinvention. Examples of such thermal initiators, without limitation,include substituted or unsubstituted organic peroxides, azo compounds,pinocols, thiurams, and mixtures thereof. Specific examples, withoutlimitation, include benzoyl peroxide, p-chlorobenzoyl peroxide, cumenehydroperoxide, 1,2-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane,2,2′-azo-bis-isobutyrylnitrile (AIBN),(1-phenylethyl)azodiphenylmethane,dimethyl-2,2′-azobis(1-cyclohexanecarbonitrile) and2,2′-azobis(2-methylpropane).

The free radical generating initiator, either photo or thermal, may bepresent in the polymerizable compositions in a selected amountsufficient to effect polymerization of the composition upon exposure tosufficient energy of the appropriate type. For example, a photoinitiatoris present in an amount sufficient to effect polymerization uponexposure to actinic radiation; generally in an amount in the range ofapproximately 0.01 to 10 wt. % of the overall composition, but moreusually in the range of approximately 0.1-6 wt. %. Mixtures of differentinitiators can be use. In certain instances, for example, when curing byuse of electron beam radiation, the composition may not require a freeradical initiator since such free radicals may be generated in situ bythe electron beam. In such instances the use of the initiator may beconsidered optional, and it may be included to facilitate or speed-uppolymerization. Additional examples of photo- and thermal initiators maybe found in publications known to those skilled in the art; for example,W. R. Sorenson and T. W. Campbell, Preparative Methods in PolymerChemistry, 2^(nd) Ed. (Interscience Publishers, New York 1968).

The following non-limiting examples serve to illustrate the compounds ofthe invention and the method of making such compounds.

Synthesis of the Compound of Structure 1.

The compound of Structure 1,3,5-difluorotris-2,4,6-(pentafluorophenyloxy)-styrene, was preparedaccording to the following overall reaction scheme, which is furtherdescribed in Examples 1 and 2.

EXAMPLE 1

Preparation of tris(pentafluorophenyloxy)benzaldehyde Formula: C₂₅HF₁₇OMolecular Weight: 688.25 g/mol.

Reaction

Pentafluorobenzaldehyde (30.00 g; 0.152 mol; 196.02 g/mol; 1 eq.),potassium carbonate (34.89 g; 0.253 mol; 138.2 g/mol; 1.65 eq.,18-crown-6 ether (18-C-6, 13.35 g; 0.051 mol; 264.32 g/mol; 0.33 eq.),and dry THF (60 ml; 2 v) were introduced in a reactor. The mixture wasstirred and refluxed gently (bp=67° C.). A solution of pentafluorophenol(92.96 g; 0.505 mol; 184.08 g/mol; 3.3 eq.) and dry THF (60 ml) wasdropped slowly into the reactor over about 1 hour. The reaction mixturebecame yellow. The mixture was refluxed during 3 days and the end iscontrolled by TLC (silica; toluene/heptane 50/50; R_(f)=0.66). If themixture is too compact (e.g., by formation of KF and/or evaporation ofTHF through the joint), dry THF was added to compensate.

When the reaction was completed, 400 ml of water were added and themixture was filtrated. The pink solid was washed by water and then driedin a dessicator. The yield of dry pinkish crude solid m=91.6 g (87%).

Purification:

The pink solid (m=91.6 g) was recrystallized from isopropyl alcohol, THFand water. The solid was dissolved by refluxing isopropyl alcohol (450ml) followed by the slow addition of THF (approximately 50 ml) until thesolution becomes clear. Water (200 ml) was added and a white solidprecipitated from the refluxing mixture. This solution was cooled at 5 °C. in ice/water slush, filtrated and the solid was washed with 60 ml ofcold isopropyl alcohol. A purified white solid was obtained, m=49.63 g(54% from the crude mixture; 47% from pentafluorobenzaldehyde).

Analysis:

Mp=132° C.

TLC: (silica C₁₈; methyl alcohol and water 90/10) R_(f)=0.26

IR (cm⁻¹): 1709.00 (C═O aldehyde), 1624.36; 1517.9 (C—F); 1490.85;1473.40; 1392.84; 1366.94; 1311.09; 1288.4; 1166.97; 1099.12; 1034.72;989.72; 948.17; 905.94; 822.62; 731.07; 621.45; 602.18

EXAMPLE 2

Preparation of 3,5-difluorotris-2,4,6-(pentafluorophenyloxy)styreneFormula: C₂₆H₃F₁₇O₃ Molecular Weight: 686.28 g/mol

Reaction

Triphenylphosphonium methylide was prepared under nitrogen from sodiumhydride and methyl triphenylphosphonium bromide in anhydrous THF. Sodiumhydride (1.16 g, 0.029 mol; 24 g/mol; 2.0 eq., 60% mineral oildispersion) was washed with anhydrous pentane (3×10 ml). The residualpentane was removed under vacuum. Under nitrogen, methyltriphenylphosphonium bromide (6.22 g; 0.0174 mol; 357.24 g/mol; 1.2 eq.)and dry THF (100 ml) were mixed together and the mixture (white) wasstirred at room temperature for approximately 15 minutes.Trisfluorophenol-benzaldehyde (10.0 g; 0.0145 mol; 688.25 g/mol; 1 eq.)was slowly added in small portions over approximately 20 minutes to thewhite mixture. The resulting was yellow. The reaction was stirred atroom temperature and the end point determined by TLC (silica;toluene/heptane 20/80; R_(f)=0.80). At completion the reaction mixturewas brown.

When there is no more starting product, toluene (100 ml) was added andthe resulting mixture was slowly quenched with water (100 ml). Theaqueous layer was extracted with 50 ml of toluene. Organic layers werecombined and washed with water (60 ml); aqueous ammonium chloride at 10%(2×80 ml); and saturated aqueous sodium chloride (100 ml). The organiclayer was then dried with potassium sulfate, filtrated, stabilized with500 ppm 4-tert-buthylcathecol (TBC) and evaporated. The residue is abrown oil (m=7.26 g; 73%) which contains small amounts oftriphenylphosphine oxide.

This oil was dissolved in a minimum amount of toluene and filtrated onsilica. The resulting filtered solution was stabilized with 500 ppm TBCbefore being concentrated to an orange solid, m=6.27 g (63%).

Purification

The orange solid was dissolved in refluxing ethanol and 10% (0.6 g) ofactive carbon was added. The mixture was stirred for approximately 5minutes then hot filtrated on cellite. The filtrate was left standing torecrystallize. The purified solid is white.

Analysis

TLC: (silica; toluene and heptane 20/80) R_(f)=0.80

TLC: (silica C18; ethyl alcohol) R_(f)=0.65

Synthesis of the Compound of Structure 5.

EXAMPLE 3

Preparation of Dialdehyde

Formula: (C₁₈H₂F₈N₂O₃S₂ Molecular Weight: 502.37 g/mol

The divinyl compound of Structure 5 was prepared according to thefollowing reaction scheme:

Reaction: Preparation of the Dialdehyde Intermediate C₁₆F₈N₂O₂S₂

The dialdehyde intermediate shown in the scheme above,4,4′-[1,3,4-thiadiazole-2,5-diylbis(thio)]bis[2,3,5,6-tetrafluoro]benzaldehyde,was prepared in a manner in accordance with Example 1, except that2,5-dimercapto-1,3,4-thiadiazole was used in place of pentafluorophenol.The resulting dialdehyde,2,5-bis(4-aldehydo-2,3,5,6-tetrafluorophenymercapto)-1,3,4-thiadiazole,was isolated and used to prepare the divinyl compound of Structure 5.

Pentafluorobenzaldehyde (20.0 g; 0.120 mol; 196.02 g/mol; 1 eq.),potassium carbonate (15.5 g; 0.112 mol; 138.2 g/mol; 2.2 eq.),18-crown-6 ether (1.35 g; 5.1×10⁻³ mol; 264.32 g/mol; 0.1 eq.) andanhydrous THF (80 ml) were introduced into a reactor and stirred. Theresulting solution was yellow.

A solution of 2,5-dimercapto-1,3,4-thiadiazole (7.66 g; 0.0515 mol;150.23 g/mol; 0.5 eq.) in anhydrous THF (30 ml) was then added at roomtemperature to the reactor over approximately 1 hour. The reaction endpoint was controlled by TLC (silica; toluene, R_(f)=0.3). The mixturewas composed of two phases: a yellow solid and a brown liquid.

When there was no more pentafluorobenzaldehyde, the mixture was quenchedwith 200 ml of water and extracted with 100 ml of dichloromethane. Theaqueous layer was then extracted with dichloromethane (3×100 ml). Thecombined organic extracts were washed with water until neutral pH. Theorganic layer was then washed with 100 ml of saturated aqueous sodiumchloride, dried with potassium sulfate, filtered, and concentrated.Subsequently, the organic solution was concentrated (beforecrystallization) and this solution was filtrated on silica. The filteredsolution was concentrated and yielded 21.7 g (84%) of a slightly yellowoil which crystallized to white solid on standing.

Analysis

Mp=132° C.

TLC: (silica C₁₈, methanol/water 9/1) R_(f)=0.74

IR (in cm⁻¹): 1710.6 (C═O aldehyde); 1640.69; 1474.05 (C-F); 1419.35;1380.17; 1349.52; 1285.64; 1037.22; 996.89; 968.24; 849.46; 787.80;631.04

EXAMPLE 4

Preparation of the Divinyl Compound of Structure 5

2,5-bis[(4-ethenyl-2,3,5,6 tetrafluorophenylsulfanyl]-1,3,4-thiadiazole

Formula: C₁₈H₆F₈N₂S₃ Molecular Weight: 498.42 g/mol

Reaction.

Triphenylphosphonium methylide was prepared under nitrogen from sodiumhydride and methyltriphenylphosphonium bromide in anhydrous THF. Sodiumhydride (2.86 g, 7.17×10⁻² mol; 24 g/mol; 2.4 eq., 60% mineral oildispersion) was washed with anhydrous pentane (3×50 ml). The residualpentane was removed under vacuum. Under nitrogen, dry THF (200 ml) andmethyltriphenylphosphonium bromide (25.6 g; 7.17×10⁻² mol; 357.24 g/mol;2.4 eq.) were mixed. The resulting white mixture was stirred at roomtemperature for approximately 15 minutes. Subsequently, the dialdehyde(15.0 g; 2.98×10⁻² mol; 502.37 g/mol; 1 eq.) from Example 3 was addedslowly to the white mixture in small portions over approximately 30minutes. The color of the resulting mixture was brown (milk-coffeecolor). The reaction was then stirred at room temperature and the endpoint determined by TLC (silica; toluene; R_(f)=0.65). When there is nomore dialdehyde or intermediate compound, toluene (100 ml) was added andthe mixture was then slowly quenched with water (200 ml). The aqueouslayer was extracted with 100 ml of toluene. Organic layers were combinedand washed with water (200 ml); aqueous chloride ammonium at 10% (200ml); and saturated aqueous sodium chloride (200 ml). The organic layerwas then dried with potassium sulfate, filtrated, stabilized with 1000ppm of 4-tert-butylcatechol (TBC) and evaporated. The residue was abrown oil (14.78 g) that contained triphenylphosphine oxide.

This brown oil was dissolved in a minimum of toluene and filtrated onsilica. The resulting solution was then stabilized with 1000 ppm TBCbefore concentrating to obtain a yellow solid m=11.13 g (75%) whichcontained a small amount of an unknown impurity.

Purification

The yellow solid (m=11.13 g) was recrystallized from ethanol and water.The solid was dissolved in refluxing ethanol. When the solution waslimpid, water was added until the solution becomes cloudy (approximately23% of water). This solution was cooled very slowly at room temperature.The resulting white solid was filtrated and washed with cold ethanol.White solid m=7.79 g (81%)

Analysis

TLC: (silica; toluene) R_(f)=0.65

IR (cm⁻¹): 3092.60 and 3032.15 (R—CH═CH2); 1600.01; 1488.16 (C—F),1437.90; 1384.41; 1266.06; 1235.26; 1194.73; 1178.52; 1129.89; 1118.54;1053.70; 914.28 and 893.21 (deformation of CH═CH2); 864.03; 711.64;669.49; 645.17

EXAMPLE 5

Synthesis of the Compound of Structure 2

The compound of Structure 2,3,5-difluorotris-2,4,6-(pentafluorothiophenyloxy)styrene, was preparedaccording to the procedures used in Examples 1 and 2 to prepare3,5-difluorotris-2,4,6-(pentafluorophenoxy)styrene, except thatpentafluorothiophenol was used in place of pentafluorophenol.

EXAMPLE 6

Synthesis of the Compound of Structure 3

The compound of Structure 3,3,5-difluorotris-2,4,6-(pentachlorophenyloxy)styrene, was preparedaccording to the procedures used in Examples 1 and 2 to prepare3,5-difluorotris-2,4,6-(pentafluorophenoxy)styrene, except thatpentachlorophenol was used in place of pentafluorophenol.

EXAMPLE 7

Synthesis of Mixed Compounds

Compounds having a mixture of pentafluorophenoxy andpentafluorothiophenoxy groups can be prepared using methods describedherein. Since such reactions may result in a mixture of compounds,separation techniques such as column chromatography, fractionalcrystallization, thin plate chromatography and similar methods known inthe art may be required to separate different compounds. To prepare suchcompounds one would adjust the phenolic content so that the total phenolcomprises, for example, 1-part pentafluorophenol and two partspentafluorothiophenol, or visa versa. Adjusting the phenolic componentin such a manner will result in a compound containing onepentafluorophenoxy groups and two pentafluorothiophenoxy groups, or visaversa, or a mixture of compounds which may be separated. Othercombinations of pentafluorophenol, pentachlorophenol andpentafluorothiophenol are possible and are deemed to be within the scopeof the invention.

EXAMPLE 8

Other Heterocycle-Containing Styrene Compounds

Trithiocyanuric acid (1,3,5-triazine-2,4,6-trithiol), C₃N₃(SH)₃, a C—Nheterocyclic compound having three pendent—SH groups, can be used inplace of 2,5-dimercapto-1,3,4-thiadiazole in reactions according toExamples 3 and 4 to form a product,2,4,6-tris(4-ethenyl-2,3,5,6-tetrafluorophenyl)-1,3,5-triazine, havingthree pendent tetrafluorostyryl groups wherein the vinyl is the paraposition relative to the sulfur atom. Other heterocyclic compoundshaving two or more pendent—SH groups can be used to prepare similarcompound in accordance with the invention.

EXAMPLE 9

Polymerizable Compositions

A polymerizable composition is prepared comprising 40 parts by weightthe compound of Structure 1, 58 parts by weight of an acrylate offormula CH₂═CA—C(O)—O—R_(f2), where A is CF₃ and R_(f2) is a highlyfluorinated C₂ alkyl group, and 2 parts by weight Darocur 1173 as aphotoinitiator. The composition is spin coated on a silicon substratehaving an undercladding layer previously applied thereto and is then UVcured through a photomask to form a waveguide structure. Uncuredcomposition is removed by use of a solvent and an overcladding layer isapplied.

Compounds containing a combination of —SH and —NH₂ groups can also beused to prepare styryl derivatives in accordance with the invention. Forexample, 5-amino-1,3,4-thiadiazole-2-thiol can be used in reactionsaccording to Examples 3 and 4 to prepare a compound having the inventionformula (p—H₂C═CH—)C₆F₄—NH—C₂N₂S—C₆F₄ —(p—CH═CH₂). In another example,4,5-diamino-2,6-dimercapto-pyrimidine can be used in reactions accordingto Examples 3 and 4 to prepare compound in which the sulfur and/or theamino groups have pendent tetrafluorophenylstyryl groups. An additionexample of an amino bearing compound that can be used in practicing theinvention is:

Absorption losses at 1550 nm are linked to C—H overtones andcombinations bands. The absorption losses at 1550 nm of several organicmolecules having various amounts of C—H bonds per volume unit and no C—Hor C-h bonds were measure using 1 mm and 10 mm optical paths to cancelerror due to interfacial reflection or diffusion. FIG. 1 illustrates theresults obtained for model molecules (hexafluorobenzene,pentafluorostyrene, phenyl trimethylsilyl acetylene and epithiopropylmethacrylate, shown as “ ” in FIG. 1) and for fluoroacrylate monomersknown in the art which bear fluoroalkoxy and fluoroalkyl chains (shownas “o” in FIG. 1) such as monomers described in U.S. Pat. Nos.6,303,563, 6,335,149 and 6,323,361 (for example, compounds of generalformula A—R₁—R_(f)—R₂—A and A—R₁—R_(f)—R₃, where A is a polymerizablegroup such as Y₂C═C(X)COO—; R₁ and R₂ are alkyl, aromatic, ester, ether,CF₂ and similar connecting groups; R₃ is CF₃, CH₃, H or D; X is H, D, F,Cl, CF₃ or CH₃; Y is H or D; and R_(f) is a fluorinated connecting groupsuch as —(CF)_(x)—, where x is 1-10. Exemplary monomers areH₂C═C(F)—C(O)O—CH₂(CF₂)₂CH₂—O(O)C—C(F)═CH₂, H₂C═C(F)—C(O)O—CH₂(CF₂)₂CH₃and H₂C═C(F)—C(O)O—CH₂(CF₂)₂CF₃. The amount of C—H per volume unit(“H/vol (I)” in FIG. 1) was estimated for the monomers. For monomersStructures 1, 2, and 3, the number of H/I is below 10, resulting in anabsorption loss estimate below 0.1 dB/cm. The estimated H/I ratio forthe monomer of Structure 1 (Compound 1) is approximately 7, resulting ina loss of 0.088 dB/cm using the linear regression curve developed fromthe model molecules.

Free-radical homopolymerization of the monomer of Structure 1, acream-white solid, was done in THF solution (800 mg of compound 1 in 20ml THF, under nitrogen, 16 hours refluxed), withazo-bis-isobutyrylnitrile (AIBN, 2 wt. %) as the initiator. A palecolored polymer was obtained. The reaction was followed by FT-IRspectroscopy.

FIG. 2 shows the FT-IR spectrum of monomer 1 (A, blue) superimposed onthe spectrum of the polymer (B, red). In the monomer spectrum bandsappears between 900 and 1000 cm⁻¹. These bands can be attributed todeformation vibration of RHC═CH₂ vinyl bonds. These bands have almostdisappeared in the polymer spectrum, indicating that the vinyl bondshave disappeared as expected for a polymerized product.

FIG. 3 shows the FT-IR spectrum of polymerized compound 1 (B, red) andthe FT-IR spectrum of copolymer 12 (C), a vinyl-epoxy fluoropolymer usedas core material for waveguides. Spectra are normalized to highest peakcorresponding to the C═C bands. The bands appearing between 2800 and3100 cm⁻¹ are attributed to the C—H stretching vibration. The bands aremuch weaker for B than for C. Consequently, when B is used intelecommunications applications a much smaller contribution toabsorbance losses due to C—H overtone and combination bands at 1550 nmis to be expected. The epoxy monomer used to prepare the copolymer wascomposed of 10 wt. % of gycidylmethacrylate, 15 wt. % oftrifluoroethylmethacrylate and 75 wt. % of pentafluorostyrene.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus it isintended that the present invention cover the modifications andvariations of this invention provided that they come within the scope ofthe appended claims and their equivalents.

1. Vinyl aromatic compounds having the formula P₂C═CH—C₆X_(4-n)Z_(n),wherein (a) P=H or D, Z=—Y—C₆X₅, —Y—W—U-[(o-, m-, p-C₆X₄—CH═CH₂)]_(m),and mixtures thereof; (b) independently, Y and U=O, S, NH, or is notpresent; (c) W is a linking group selected from the group consisting ofaromatic, polycyclic aromatic (fused-ring), 5- or 6-member heterocyclicaromatic and polycyclic-heterocyclic compounds and halogenatedderivatives thereof; (d) X=F, Cl, CF₃ and R_(f), and mixtures thereof,and R_(f) is a C₂-C₅ hydrocarbon in which 50% or more of C—H bonds arereplaced by C—F bonds; and (e) m and n are integers in the range of 1-3.2. The compounds according to claim 1, wherein W is a 5- and 6-memberheterocyclic ring system having pendent from the heterocyclic ring atleast two thiol groups, or an amino group and a thiol group, or aplurality of amino and/or thiol groups.
 3. The compounds according toclaim 2, wherein the heterocyclic ring is selected from the groupconsisting of pyridine, s- or as-thiazine, thiazoles, triazines,dithiazines, thiadiazines, pyrazine, pyrimidine, pyridazine, indolizine,imidazole, thiadiazoles, thiophene, furan, halogenated derivativesthereof, and similar compounds known in the art.
 4. The compoundsaccording to claim 2, wherein the heterocyclic aromatic ring is selectedfrom the group consisting of 1,3,4-thiadiazole-2,5-dithiol;5-amino-1,3,4-thiadiazole-2-thiol; trithiocyanuric acid;4-amino-2-mercaptopyrimidine; 2,4-diamino-6-mercaptopyrimidine;4,6-diamino-2-mercaptopyrimidone; 4,5-diamino-2,6-dimercaptopyrimidine,halogenated derivatives thereof, and similar compounds known in the art.5. The compounds according to claim 1, wherein one or both of U and Y isabsent, and W is a polycyclic heterocyclic ring having a —N<(in ring) inplace of said absent Y or U, and halogenated derivatives of said ring.6. The compounds according to claim 5, wherein W is selected from thegroup consisting of 1,2-difluoro-2,3,5,6-benzenetetracarboxylic aciddiimide, alloxazine {benzo[g]pteridine-2,4(1H,3H)-dione},2-amino-6-chloropurine, 2-amino-6-hydroxy-8-mercaptopurine,5-aminoindazole, 5-aminoindole, 1-aminopyrine, 2-amino-6-purinethiol andsimilar compounds known in the art, and halogenated derivatives thereof.7. The compounds according to claim 1, wherein Z is selected from thegroup consisting of —O—C₆F₅, —O—C₆Cl₅, —S—C₆F₅, —S—C₆Cl₅, and mixturesthereof, and n=3.
 8. The compound according to claim 1, wherein n=1 andZ is: